AbstractAnisotropic water diffusion in neural fibres such as nerve, white matter
in spinal cord, or white matter in brain forms the basis for the utilization of
diffusion tensor imaging (DTI) to track fibre pathways. The fact that water
diffusion is sensitive to the underlying tissue microstructure provides a unique
method of assessing the orientation and integrity of these neural fibres, which
ma... hiện toàn bộ
AbstractThe state of the art of reconstruction of the axonal tracts in the
central nervous system (CNS) using diffusion tensor imaging (DTI) is reviewed.
This relatively new technique has generated much enthusiasm and high
expectations because it presently is the only approach available to
non‐invasively study the three‐dimensional architecture of white matter tracts.
While there is no doubt that ... hiện toàn bộ
AbstractThe LCModel method analyzes an in vivo spectrum as a Linear Combination
of Model in vitro spectra from individual metabolite solutions. Complete model
spectra, rather than individual resonances, are used in order to incorporate
maximum prior information into the analysis. A nearly model‐free constrained
regularization method automatically accounts for the baseline and lineshape in
vivo wit... hiện toàn bộ
AbstractWe review several methods that have been developed to infer
microstructural and physiological information about isotropic and anisotropic
tissues from diffusion weighted images (DWIs). These include Diffusion Imaging
(DI), Diffusion Tensor Imaging (DTI), isotropically weighted imaging, and
q‐space imaging. Just as DI provides useful information about molecular
displacements in one dimensio... hiện toàn bộ
AbstractMolecular and cellular MR imaging is a rapidly growing field that aims
to visualize targeted macromolecules or cells in living organisms. In order to
provide a different signal intensity of the target, gadolinium‐based MR contrast
agents can be employed although they suffer from an inherent high threshold of
detectability. Superparamagnetic iron oxide (SPIO) particles can be detected at
mi... hiện toàn bộ
AbstractThis article treats the theoretical underpinnings of diffusion‐tensor
magnetic resonance imaging (DT‐MRI), as well as experimental design and data
analysis issues. We review the mathematical model underlying DT‐MRI, discuss the
quantitative parameters that are derived from the measured effective diffusion
tensor, and describe artifacts thet arise in typical DT‐MRI acquisitions. We
also dis... hiện toàn bộ
Afonso C. Silva, Jeong Yong Lee, Ichio Aoki, Alan P. Koretsky
AbstractManganese‐enhanced MRI (MEMRI) is being increasingly used for MRI in
animals due to the unique T1 contrast that is sensitive to a number of
biological processes. Three specific uses of MEMRI have been demonstrated: to
visualize activity in the brain and the heart; to trace neuronal specific
connections in the brain; and to enhance the brain cytoarchitecture after a
systemic dose. Based on ... hiện toàn bộ
AbstractDiffusion NMR is the only method available today that noninvasively
provides information on molecular displacements over distances comparable to
cell dimensions. This information can be used to infer tissue microstructure and
microdynamics. However, data may be fairly difficult to interpret in biological
tissues which differ markedly from the theoretical “infinite isotrope medium”,
as many... hiện toàn bộ
Wei Li, Alexandru Avram, Bing Wu, Xue Xiao, Chunlei Liu
Quantitative susceptibility mapping (QSM) is a recently developed MRI technique
that provides a quantitative measure of tissue magnetic susceptibility. To
compute tissue magnetic susceptibilities based on gradient echoes, QSM requires
reliable unwrapping of the measured phase images and removal of contributions
caused by background susceptibilities. Typically, the two steps are performed
separatel... hiện toàn bộ